Gun for pinch fasteners

ABSTRACT

An applicator gun for pinch fasteners of the type resembling a large-headed nail used for securing thick, soft slabs of insulation material to sheet metal, the shank of said fastener being adapted to pierce said insulation slab to abut the underlying sheet metal, and being specially formed to pinch and permanently grip said sheet metal responsively to hammer blows delivered to the head of said fastener, said applicator gun consisting of a carriage movable on a rail above a table supporting said sheet metal and insulation panels, a pneumatic hammer carried by the carriage with its head normally retracted above said panels, a feed mechanism carried by said carriage and operable to deliver fasteners one at a time to said hammer head while in its retracted position, said fastener being retained magnetically on said hammer head, hammer control mechanism carried by said carriage and operable to advance said hammer to cause the shank of said fastener to pierce said insulation and abut said sheet metal, and then to actuate said hammer to deliver hammer blows to the head of said fastener, a single lever operable to control both said feed mechanism and said hammer control mechanism, and an interlock operable to prevent any possible interference between said feed mechanism and said hammer.

United States Patent Saluzzi 1 51 May 30, 1972 1541 GUN FOR PINCH FASTENERS 15 1 RAC [72] Inventor; F ank sal j, 5218 N h Fl Kansas An applicator gun for pinch fasteners of the type resembling a Ci M 64] 18 large-headed nail used for securing thick, soft slabs of insulation material to sheet metal, the shank of said fastener being [22] Filed: 1970 adapted to pierce said insulation slab to abut the underlying [21] Appl.No.: 67,316 sheet metal, and being specially formed to pinch and permanently grip said sheet metal responsively to hammer blows delivered to the head of said fastener, said applicator gun con- Efi] ..227/110,;27/1l6 Sisting ofa carriage movable on a ran above a table Supporting d said sheet metal and insulation panels, a pneumatic hammer 1 1e 0 1 carried by the carriage with its head normally retracted above said panels, a feed mechanism carried by said carriage and [56] References Cited operable to deliver fasteners one a t a time to said hammer head while in its retracted position, sa1d fastener being UNITED STATES PATENTS retained magnetically on said hammer head, hammer control mechanism carried by said carriage and operable to advance i g i said hammer to cause the shank of said fastener to pierce said 0 nson l t d t d h d t t 3,065,470 11/1962 Schmidt ..227/1s x a an S eel metal Primary Examiner-Granville Y. Custer, Jr. Alt0rney.lohn A. Hamilton hammer to deliver hammer blows to the head of said fastener, a single lever operable to control both said feed mechanism and said hammer control mechanism, and an interlock operable to prevent any possible interference between said feed mechanism and said hammer.

10 Claim, 13 Drawing Figures PATENTEDHAY 30 I972 SHEET 10F 4 PATENTEDMAY 30 m2 SHEET 2 0F 4.

Fig.4,

I NVENTOR Han/f Ja/uzz/ a, W

Affamey.

GUN FOR PINCH FASTENERS This invention relates to new and useful improvements in applicator guns for a relatively new type of mechanical fastener which may be designated generally as a pinch fastener, although perhaps more commonly known as grip nails", although the latter term is not here used since it constitutes a proprietary trade mark.

Such fasteners, which are used for example to secure sheets of fibrous or other insulating material to sheet metal panels which are later assembled to form ducting for heating and airconditioning systems, constitute devices resembling largeheaded nails the shanks of which pierce the insulating material to abut the sheet metal, the end of the shank being specially formed in such a manner that when sharp hammer blows are then delivered to the fastener head, it gouges into and pinches the sheet metal, but without penetrating it, to form a secure connection. This type of fastener has many desirable features, being fast and convenient, and requireing no heat. Also, the lack of penetration of the sheet metal is quite important in many applications, particularly in duct work where penetration causes leakage of air. The fastener can be applied without penetration to sheet metal at least as thin as 24-gauge.

However, to my knowledge, there has been no effective applicator gun developed for this type of fastener, and the provision of such an applicator gun, of at least semi-automatic character, is the object of the present invention. The problems attendent on the provision of such an applicator gun arise from the special nature of the fastener itself. From a loading position remote from the panels to be joined, where a fastener is connected to a tool for making the connection, the tool must be advanced with considerable force to cause the shank to penetrate the insulation layers and hold the point of said shank against the sheet metal with considerable force while hammer blows are delivered to the head of the fastener. Thus, while the tool to which the fastener is applied may physically constitute the hammer for delivering the final blows, the ower means for advancing the hammer to cause penetration must be separate from the power means for delivering the blow, since both power means must operate simultaneously at the moment of the hammer blows. Merely advancing the tool with sufiicient force to drive the fastener through the insulation and to engage the sheet metal with hammer blow force, by means of a single power means, would result in rebounding of the fastener from the sheet metal panel, with little likelihood of a secure connection therebetween. To prevent this occurrence, the present structure utilizes a complete pneumatic hammer, including a housing, mandrel, hammer head and operating striker means within the housing, said hammer being bodily movable in a carriage by a pneumatic ram, said ram advancing the hammer bodily to cause the shank of the fastener carried thereby to pierce the insulation and be pressed firmly against the sheet metal, whereupon the hammer itself is actuated.

Another object is the provision of an applicator gun of the character described, wherein said hammer and its advancing rarn are mounted in a carriage movable on a rail disposed above a table on which the insulation and sheet metal panels to be joined are rested.

A further object is the provision of an applicator gun of the character described including a feed mechanism operable to deliver fasteners one at a time from a magazine mounted on said carriage to apply them to the head of said hammer when said hammer is in its retracted position.

A still further object is the provision of an applicator gun of the character described wherein both the hammer advancing ram and the feed mechanism are controlled by a single pluralposition lever on said caniage, said lever being provided with interlock means whereby said hammer cannot be advanced while the feed mechanism is operative, and said feed mechanism cannot be actuated while said hammer is advanced.

Other objects are simplicity and economy of structure, and convenience, efficiency, and dependability of operation.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the accompanying drawing wherein:

FIG. 1 is a side elevational view, with parts broken away, of an applicator gun embodying the present invention, shown in a neutral position,

FIG. 2 is a view similar to FIG. 1, but showing the applicator gun in its loading position,

FIG. 3 is a view similar to FIG. 1, but showing the applicator gun in its firing position,

FIG. 4 is a rear elevational view of the applicator gun as shown in FIG. 3,

FIG. 5 is a sectional view taken on line V-V of FIG. 2,

FIG. 6 is an enlarged, fragmentary sectional view taken on line VI-VI of FIG. 5, showing the fastener feeder bar advanced,

FIG. 7 is a view similar to FIG. 6, but showing the fastener feeder bar retracted,

FIG. 8 is a fragmentary sectional view taken on line VIIl VIII of FIG. 7,

FIG. 9 is a fragmentary sectional view taken on line IX-IX of FIG. 7, with the fasteners omitted,

FIG. 10 is a schematic pneumatic flow diagram of the applicatorgun,

FIG. 11 is an enlarged longitudinal sectional view of one of the pinch fasteners, shown with its shank disposed against a sheet metal panel preparatory to being secured thereto by hammer blows,

FIG. 12 is a view similar to FIG. 11, but showing the fastener after it has been secured by hammer blows thereon, and

FIG. 13 is an enlarged end view of the shank of the fastener as shown in FIG. 11.

Like reference numerals apply to similar parts throughout the several views, and FIGS. 11-13 show details of one of the pinch fasteners adapted to be applied by the applicator gun forming the subject matter of the present invention. Said fastener is indicated generally by the numeral 2, and includes a solid, nail-like mandrel 4 having a head 6 and a cylindrical metal sheath 8 enclosing and rigidly affixed to said mandrel, said mandrel and sheath constituting the shank of the fastener, although for convenience the shank will hereinafter be designated by the numeral 8. Sheath 8 may be formed to present an enlarged sheet metal head 10 normal to the shank and underlying mandrel head 6. Head 10 may be of circular or other desired shape, and of any desired size. The free end of sheath 8 extends beyond the free end of mandrel 4, the extended portion thereof being taperingly reduced in diameter, as indicated at 12, and diametrically slotted as indicated at 14. The fastener is secured to a sheet metal panel 16 supported by a rigid table or other fixed support 18 by first pressing the tapered end 12 of the fastener shank firmly against panel 16, normally thereto, as shown in FIG. 11, then delivering sharp hammer blows to mandrel head 6. As shown in FIG. 12, this causes tapered portion 12 of sheath 8 to collapse radially inwardly, the hardness and stiffness thereof, as compared to that of sheet metal 16, being sufficient that during its inward collapse, it gouges into sheet 16 and pinches a portion of the metal of said sheet upwardly between the ends of tapered portion 12 of the sheath at opposite sides of slot 14, as indicated at 20 in FIG. 12, thereby effecting a permanent connection sufficiently secure for the purposes intended. A slab or panel 22 of insulating material or the like (see FIGS. l-5), through which the fastemer shanks were pierced prior to the hammer blows, is then securely fastened between metal sheet 16 and the enlarged heads 10 of the fasteners.

The applicator gun forming the subject matter of the present invention is carried by a fixed horizontal rail 24 disposed in spaced relation above table 18, on which metal sheet 16 and slab 22 of insulating material to be secured thereto are laid as shown. The applicator gun includes a carriage 26 formed by a pair of vertical, parallel side plates 28 rigidly connected together by a series of horizontal spacer plates 30. Rail 24 extends between the upper end portions of side plates 28, and is engaged, along both its upper and lower edges, by horizontal rollers 32 joumalled rotatably in said side plates, whereby the carriage is supported for rolling movement along said rail.

Mounted between side plates 28, just below rail 24, is a pneumatic cylinder 34, said cylinder being vertical and being affixed between a pair of spacer plates 30. Said cylinder is double-acting, being provided (see FIG. with a piston 36 and ports 38 and 40 respectively at its upper and lower ends whereby air may be selectively delivered to or exhausted therefrom above and below the piston. A piston rod 42 affixed to piston 36 extends vertically downwardly from the cylinder, and has a crosshead 44 affixed to its lower end. Suspended from said crosshead by bolts 46 is a horizontal clamp ring 48. Said bolts have a longitudinal sliding connection with either the crosshead or the clamp ring, and compression springs 50 carried on said bolts are confined between said crosshead and said clamp ring. A pneumatic hammer 52 includes a housing 54 about which clamp ring 48 is rigidly clamped by clamp bolt 56. A mandrel 58 is carried movably by housing 54 and extends vertically downwardly therefrom, being equipped at its lower end with a hammer head 60, which it will be understood is formed of magnetic material. The internal construction of the hammer is well-known in the art and is not here shown. Housing 54 has an inlet port 62 for compressed air, which operates a striker 63 within the housing (see FIG. 10) for delivering hammer blows to the upper end of mandrel 58 whenever an external trigger 64 carried by the housing is depressed. Crosshead 44 and hammer 52 are disposed below the forward portion of carriage 26, in front of a downwardly extending rearward portion of said carriage. The head 60 of hammer 52 is movable by the action of cylinder 34 from an elevated position well above slab 22 of insulation supported on table 18, as shown in FIGS. 1, 2, S, and 7, downwardly to a position substantially engaging said insulation, as shown in FIGS. 3, 4, and 6. As it reaches said lower position, trigger 64 is engaged and depressed by the upper end of a trip screw 66 which is fixed for vertical adjustment in a bracket 68 by means of a pair of lock-nuts 70. Bracket 68 is rigidly affixed to a side wall 28 of the carriage.

A supply of fasteners 2 are carried in a magazine 72 constituting a vertically extending C-shaped channel disposed between side plates 28 and extending from a point at about the same level as the upper end of cylinder 34 downwardly to the feed mechanism at the lower end of the carriage as will be described. Said channel is of rectangular cross-sectional contour, of such dimensions as to carry the heads 10 of said fasteners in edge-to-edge stacked relation therein, as shown in FIGS. 6-8. Said heads are freely slidable in said channel so as to move downwardly therein by gravity. The channel is provided along the midline of its rearward wall with a longitudinal slot 74, and the shanks 8 of the fasteners extend rearwardly through said slot. The channel is affixed by any suitable means, not shown, to the rearward edges of certain of spacer plates 30. The fasteners are loaded into the magazine from the upper end thereof.

The feed mechanism is best shown in FIGS. 6-9. It includes an elongated horizontal slide bar 76 which is horizontal and extends from front to rear, being carried for longitudinal sliding movement in a groove 78 formed in the lower surface of a thick horizontal plate 80 secured between side plates 28 at the lower end of the carriage, as by screws 82, said slide bar being retained slidably in said groove by a horizontal plate 84 underlying plate 80 and groove 78 thereof, and secured to side plate 28 by screws 86 (see FIG. 8). Plates 80 and 84 have their forward edges flush with the forward edges of side plates 28, well behind the normal path of travel of hammer 52. The lower end of magazine channel 72 abuts the upper surface of plate 80, adjacent the forward edge thereof.

Plate 80 has a notch 88 formed in the forward edge thereof, said notch being sufficient transverse width to admit the head 10 of a fastener 2 therein, and extending rearwardly of magazine channel 72 to a distance less than the extension of the fastener shanks 8 from said channel, and a narrower notch 90 extending rearwardly from notch 88 to a distance greater than the rearward extension of the fastener shanks. Slide bar 76 is movable from a retracted position in which its forward end is generally flush with the forward edges of plates and 84, as shown in FIG. 7, to an advanced position wherein the forward end thereof is disposed beneath head 60 of hammer 52, as shown in FIG. 6. The forward end of slide bar 76 has a forwardly opening notch 92 formed therein, said slot being of a width to admit the fastener shanks therein, and extending rearwardly, when said slide bar is retracted, farther than the rearward extension of the shanks of the fasteners in magazine channel 72. Plate 84 has a notch 94 formed in the forward edge thereof, said notch being coextensive with notch 92 of the slide bar when the latter is retracted. The slide bar also has a notch 96 formed in the upper surface thereof at its forward end, said notch opening through the top and forward surfaces of said bar, and extending rearwardly only to a position such that when the slide bar is retracted, as in FIG. 7, the lower edge of the head 10 of the lowermost fastener 2 in magazine channel 72 can enter therein. A drag weight 98 is pivoted on a horizontal transverse axis, as at 100, between side plates 28 of the carriage, forwardly of magazine channel 72 and just above plate 80. Said drag weight, which may constitute a block of substantial mass, normally hangs vertically downwardly, extending into notch of plate 80 and into the forward portion of notch 96 of slide bar 76, as shown in FIG. 7, but is capable of forward pivotal movement as shown in FIG. 6 when slide bar 76 is advanced.

Thus it will be seen that when slide bar 76 is retracted, as in FIG. 7, the head 10 of the lowermost fastener 2 in magazine channel 72 drops into notch 88 of plate 80 and into notch 96 of the slide bar, with shank 8 of the fastener entering notch 90 of plate 80. When the fastener has dropped this far, it tilts downwardly and rearwardly as shown, the rearward wall of channel 72 being cut away at its lower end adjacent slot 74 thereof, as best shown at 102 in FIG. 8, to free the fastener head to permit this tilting. During the tilting movement, shank 8 of the fastener drops through notch 92 of the slide bar and extends into notch 94 of plate 84, the parts then having the position shown in FIG. 7, with the next higher fastener 2 resting on the tilted lowermost fastener. Drag weight 98 obstructs the open forward ends of notches 88 and 92, so that there is no possibility that the lowermost fastener will continue forwardly and fall free of the carriage at this time. When slide bar 76 is then advanced forwardly, the rearward end of notch 92 thereof engages shank 8 of the tilted fastener and pushes said fastener forwardly from the carriage, as shown in FIG. 6. DUring this movement, drag weight 98 is pivoted forwardly as shown, resting slidably by gravity on the upper surface of the slide bar. Fastener 2, with its head 10 resting on the top of the slide bar and its shank 8 extending downwardly through notch 92, moves beneath weight 98 during advancement of the slide bar, and the dragging resistance said weight applies to head 10 insures that the shank 8 will be positioned at the extreme rearward end of notch 92. DUring this movement, the head 10 of the next fastener 2 in the magazine rests slidably on the upper surface of slide bar 76, as shown in FIG. 6, and is supported thereby in a sufficiently elevated position that its head is too high to be freed for tilting movement by cut-aways 102 of the magazine channel, and cannot tilt until it is allowed to drop into notch 96 of the slide bar when the slide bar is next retracted.

When slide bar 76 is fully extended, as in FIG. 6, the fastener 2 carried thereby is disposed directly beneath head 60 of hammer 52, coaxially therewith and very closely adjacent thereto, so long as the hammer is retracted upwardly. Since the hammer head is magnetic, and since the fastener is formed of ferrous material, the fastener head 10 is attracted upwardly to the hammer head, and retained there when slide bar 76 is retracted, as shown in FIG. 7.

Slide bar 76 is advanced and retracted by an arm 104 pivoted at its upper end, as at 106, between side plates 28 at the rearward edges thereof above said slide bar. Said arm extends downwardly into a notch 108 formed in the rearward end of the slide bar and has a longitudinal slot 110 formed therein which slidably and pivotally engages a pin 112 affixed horizontally and transversely in the slide bar to span notch 108 thereof. Adjacent pivot 106, a rearwardly extending transverse arm 114 is affixed to arm 104. A link 116 has its lower end pivoted, as at 118, to the rearward end of arm 114, and the upper end of link 116 is pivoted as at 120, to a manual operating lever 122, one end of said lever being pivoted, at a point spaced apart from pivot 120, to a bracket 124 affixed to one of carriage side plates 28, as at 126. Operating lever 122 has an elevated neutral position, shown in FIG. 1, at which slide bar 76 is retracted, and a lower depressed position, shown in FIG. 2, at which slide bar 76 is advanced. The elevated position may be termed a neutral" position, and the depressed position may be termed a loading position.

Pneumatic cylinder 34 for advancing and retracting hammer 52 is actuated by a pneumatic control valve 128 mounted on the outside of one of side plates 28 of the carriage. Compressed air from any suitable source is delivered by a hose 130 to inlet port 62 of hammer 52, and by hose 132 to valve 128. Hoses 130 and 132 must of course be flexible, to permit vertical movement of the hammer, and to permit movement of carriage 26 along rail 24. The internal details of valve 128 are not specifically pertinent, it being understood that it includes an internal slide 134 having a normal position, as shown in FIG. and to which it is biased by spring 136, in which internal passages of the slide connect the inlet port of the valve to an outlet port 138 of the valve which is connected by hose 140 to the lower port 40 of cylinder 34, the upper port 38 of said cylinder being connected by a hose 142 to a port 144 of valve 128, which is then connected by passages of slide 134 to an atmospheric exhaust port 146. In this position of valve 128, air pressure in the lower end of cylinder 34 elevates piston 36 to raise hammer 52 to its upwardly retracted position. Valve slide 134 is movable downwardly against spring 136, by mechanical pressure on an upwardly extending plunger 148, to a position wherein compressed air is delivered to the upper end of cylinder 34 through hose 142, and the lower end of the cylinder is exhausted through hose 140, whereby hammer 52 is advanced downwardly to its firing position as shown in FIG. 3.

Valve plunger 148 is operable by a lever 150 pivoted intermediate its ends, as at 152, to one of carriage side plates 28. One end 154 of said lever is disposed above the upper end of plunger 148, and the other end of said lever is pivoted, as at 156, to the upper end of a link 158, the lower end of said link being pivoted, as at 160, to operating lever 122 at a point spaced apart from pivot 126 of said lever. When operating lever 122 is in its neutral position as shown in FIG. 1, or its loading position as shown in FIG. 2, lever 154 does not engage plunger 148 and hammer 52 therefore remains elevated. However, if lever 122 is elevated slightly upwardly from its neutral position, as shown in FIG. 3, end 154 of lever 150 engages and depresses plunger 148, thereby actuating valve 128 and cylinder 34 to lower hammer 52, as already described.

An interlock bar 162 is pivoted to operating lever 122 at 160, and extends generally horizontally and forwardly therefrom to lie in sliding engagement with the outer surface of one of side plates 28 of the carriage. The bar 162 is guided for vertical pivotal movement and longitudinal movement by a keeper 164 affixed to side plate 28. The forward free end of bar 162 if biased yieldably upwardly by a spring 166, whereby a notch 168 formed in the upper edge of said interlock bar is urged toward engagement with a pin 170 fixed in side plate 28 and projecting outwardly therefrom. Notch 168 and pin 170 are so positioned that when they are interengaged, operating lever 122 can be moved freely between its neutral position of FIG. 1 and its firing position of FIG. 3, but cannot be lowered toward its loading position as shown in FIG. 2. Interlock bar 162 can be pivoted downwardly against spring 166, whereby to free notch 168 from pin 170, by means of a lever 172 pivoted intermediate its ends, as at 174, to the inner surface of side plate 28, on a horizontal transverse axis. At one end of lever 172, a pin 176 is affixed thereto and projects laterally outwardly therefrom through a hole 178 formed therefor in side plate 28 to overlie the upper edge of interlock bar 162. The opposite end of lever 172 carries a tab 180 which is engageable from below by the upper end of a push rod 182, the lower end of said push rod being affixed to and movable with crosshead 44 which supports hammer 52. Whenever hammer 52 approaches the upper limit of its retraction, push rod 182 engages tab 180 and pivots lever 172 in a clockwise direction, as viewed in FIGS. l-3, whereby pin 176 cams interlock bar 162 downwardly to free notch 168 thereof from pin 170, thereby permitting free longitudinal movement of the interlock bar and hence permitting free pivotal movement of lever 122. However, whenever hammer 52 starts its downward advancement, push rod 182 releases lever 172 and interlock bar 162 is pivoted upwardly by spring 166, so that notch 168 thereof engages pin 170 if they are aligned.

Operation of the gun is substantially as follows. Assuming first that manual operating lever 122 is in its neutral position as shown in FIG. 1, it will be seen that slide bar 76 of the feed mechanism is in its retracted position, with the lowermost fastener 2 from magazine channel 72 having dropped into tilted position with its shank 8 engaged in notch 92 of said slide bar as shown in FIG. 7, and hammer 52 is in its upwardly retracted position, since plunger 148 of valve 128 is not engaged by lever 150, so that said valve is positioned to deliver compressed air to the lower end of cylinder 34. Hammer 52 is then positioned directly over the point of insulation slab 22 and metal sheet 16 at which it is desired to apply a fastener 2. This may be done by moving carriage 26 along rail 24, and by shifting members 16 and 22 on table 18 laterally of said rail.

Operating lever 122 is then pivoted downwardly to its loading position as shown in FIG. 2. This extends slide bar 76 of the feed mechanism to position a fastener 2 on the lower face of hammer head 60 where it is magnetically retained, as previously described and as shown in FIG. 6. Hammer 52 remains in its upwardly retracted position at this time. Operating lever 122 is then again elevated to its neutral position, which retracts slide bar 76, but leaves a fastener 2 retained on hammer head 60 as shown in FIG. 7, and then upwardly past its neutral position to its firing position as shown in FIG. 3. During movement of lever 122 from its neutral position to its firing position, end 154 of lever engages and depresses plunger 148 of valve 128, said valve then functioning as previously described to exhaust the lower end of cylinder 34 and to delivery compressed air to the upper end of said cylinder. This forces piston 36 downwardly, lowering hammer 52 and the fastener 2 carried thereby. As the hammer is lowered, it causes shank 8 of the fastener to pierce the insulation slab 22 and press firmly against metal sheet 16. At this moment, trigger 64 of the hammer engages and is depressed by trip screw 66, which may be vertically adjusted by loosening lock nuts 70 to insure that said trigger is depressed at the proper moment. Hammer 52, thus actuated, delivers sharp hammer blows to head 6-10 of the fastener, causing tapered end portion 12 of shank 8 of the fastener to pinch into the upper surface of metal sheet 16, as previously described and as shown in FIG. 12. Springs 50 absorb the recoil forces imparted to hammer housing 54 by the hammer action, and serve to maintain pressure against the fastener as the hammer blows are delivered thereto. As previously pointed out, the maintenance of pressure on the fastener as the hammer blows are delivered is necessary to prevent rebounding of the fastener from metal sheet 16. Insulation slab 22 is thus securely attached to metal sheet 16. OPerating lever 122 is then returned to its neutral position of FIG. 1. This causes lever 150 to release plunger 148 of valve 128, whereupon spring 136 of said valve positions slide 134 of the valve to exhaust the upper end of cylinder 34 and deliver compressed air to the lower end thereof, so that hammer 52 is again raised to its upwardly retracted position. This completes an operating cycle.

The control of the advancement of feed slide 76, and of hammer 52, by a single operating lever, and by movement of said lever in respectively opposite directions from a neutral position in which both of said members are retracted, has the general effect of preventing the possibility that both the hammer and slide might be advanced simultaneously, which would cause interference between these members and damage thereto. At least, it provides that the advancement of hammer 52 cannot begin until feed slide 76 is fully retracted, and also that the advancement of slide 76 cannot be commenced until cylinder 34 has been set in operation to at least begin the retraction of hammer 52. However, the upward retraction of hammer 52 is not instantaneous, the operation of pneumatic cylinder 34 inherently requiring a definite, longer time period, and there therefore remains the possibility that if a human operator should move lever 122 rapidly from the firing position of FIG. 3, through the neutral position of FIG. 1, to the loading position of FIG. 2, feed slide 76 might be advanced before hammer 52 is fully retracted, so that slide 76 would ram into the side of hammer housing 54, or mandrel 58 or head 60 of the hammer, with resultant damage.

The interlock latch means including bar 162 and pin 170 prevents this occurrence. In the neutral position of FIG. 1, notch 168 of said interlock bar is aligned with pin 170 of the carriage, but the bar is pivoted downwardly to maintain said notch out of engagement with said pin by the camming action of pin 176 of lever 172 thereagainst, so long as hammer 52 is upwardly retracted to cause push rod 182 to engage tab 180 of said lever. Bar 162 is thus free to move longitudinally, and lever 122 may be pivoted downwardly to its loading position, with notch 168 then moving out of alignment with pin I70 so that the upper edge of the bar moves slidably under said pin. When lever 122 is moved upwardly to its firing position, notch 168 is in alignment with pin 170, and when the hammer is then advanced downwardly, push rod 182 disengages tab 180 of lever 172, allowing pin 176 of said lever to move upwardly, and allowing interlock bar 162 to be pivoted upwardly by spring 166 to move notch 168 into engagement with pin 170, as shown in FIG. 3. The length of notch 168, longitudinally of bar 162, is such that lever 122 can be lowered to its neutral position even when said notch is in engagement with pin 170, but cannot be lowered further toward its loading position until hammer 52 is fully retracted so that push rod 182, lever 172 and pin 76 function to cam interlock bar 162 downwardly against spring 166 to disengage notch 168 from pin 170. Thus in no event can feed slide 76 ever be advanced until hammer 52 is fully retracted out of its path.

While I have shown and described a specific embodiment of my invention, it will be readily apparent that many minor changes of structure and operation could be made without de parting from the spirit of the invention.

What I claim as new and desire to protect by Letters Patent 1. An applicator gun for applying pinch fasteners of the type consisting of a headed shank specially formed at its free end to pinch into the surface of a sheet of metal in response to hammer blows delivered to the head thereof, whereby to affix to said metal sheet a layer of insulating material pierced by said shank, said metal sheet resting on a horizontal table with said insulating material overlying said sheet, said applicator gun comprising:

a. a carriage,

b. means supporting said carriage above said table,

c. a hammer mounted movably in said carriage and including a downwardly directed head and means operable when actuated to deliver downward blows to said head,

d. hammer moving means mounted in said carriage and operable to move said hammer between a retracted position in which said hammer head is spaced above the insulation material and metal sheet supported by said table to a downwardly advanced position wherein the downwardly directed shank of a fastener carried on the lower face of said hammer head pierces said insulation material and abuts said metal sheet,

e. a fastener magazine carried by said carriage,

f. feed mechanism carried by said carriage and operable when actuated to deliver a fastener from said magazine and to apply said fastener to the lower face of said hammer head, while said hammer is in its retracted position, with the shank of said fastener directed downwardly,

. manually operable actuating means carried by said carriage and operable to actuate said hammer moving means and said feed mechanism, and

h. means mounted on said carriage and operable to actuate said hammer whenever it is moved to its advanced position.

2. The structure as recited in claim 1 wherein said means supporting said carriage above said table includes a fixed horizontal rail disposed above said table and a plurality of rollers mounted rotatably in said carriage and having rolling engagement with said rail, there being at least two of said rollers engaging the upper or lower edge of said rail in spaced apart relation, and at least one of said rollers engaging the other edge of said rail.

3. The structure as recited in claim 1 wherein said hammer moving means includes means operable to maintain a constant downward pressure on said hammer when said hammer is actuated.

4. The structure as recited in claim 1 wherein said hammer head constitutes a magnet, said fastener being formed of ferrous material, whereby a fastener applied to said hammer head by said feed mechanism will be magnetically retained thereagainst during the advancement of said hammer.

5. The structure as recited in claim 4 wherein said feed mechanism includes a feed member carried by said carriage for movement from a retracted position out of the path of said hammer to an advanced position in the path of said hammer when said hammer is retracted, whereby to apply a fastener to said hammer head, the magnetic retention of said fastener on said hammer head permitting said feed member to be retracted before said hammer is advanced.

6. The structure as recited in claim 5 wherein said manual actuating means is operable to actuate said hammer moving means and said feed mechanism selectively but not concurrently, whereby said hammer and said feed member cannot be advanced simultaneously.

7. The structure as recited in claim 5 wherein said manual actuating means comprises a lever carried by said carriage for movement in respectively opposite directions from a neutral position, means operable by movement of said lever in one direction to advance said feed member, and to retract said feed member when said lever is returned to neutral, and means operable by movement of said lever in the opposite direction to activate said hammer moving means to advance said hammer, and to actuate said hammer moving means to retract said hammer when said lever is returned to neutral.

8. The structure as recited in claim 7 wherein said hammer moving means is of a type requiring an appreciable time period after actuation thereof to advance or retract said hammer, and with the addition of interlock means operable responsively to the position of said hammer to lock said lever against movement in said one direction except when said hammer is in its fully retracted position.

9. An apparatus as recited in claim 8 wherein said interlock means comprises:

a. a latch operable when engaged to limit said lever to movement between said neutral position and the position thereof in which it activates said hammer moving means to advance said hammer,

b. means connected to and movable with said hammer and operable to disengage said latch whenever said hammer approaches its fully retracted position.

10. An apparatus as recited in claim 8 wherein said hammer moving means comprises:

said valve normally being operable to deliver fluid to the end of said cylinder to cause retraction of said hammer, said means operable by said lever including means operable by movement of said lever in said opposite direction to operate said valve to deliver fluid to the end of said cylinder to advance said hammer. 

1. An applicator gun for applying pinch fasteners of the type consisting of a headed shank specially formed at its free end to pinch into the surface of a sheet of metal in response to hammer blows delivered to the head thereof, whereby to affix to said metal sheet a layer of insulating material pierced by said shank, said metal sheet resting on a horizontal table with said insulating material overlying said sheet, said applicator gun comprising: a. a carriage, b. means supporting said carriage above said table, c. a hammer mounted movably in said carriage and including a downwardly directed head and means operable when actuated to deliver downward blows to said head, d. hammer moving means mounted in said carriage and operable to move said hammer between a retracted position in which said hammer head is spaced above the insulation material and metal sheet supported by said table to a downwardly advanced position wherein the downwardly directed shank of a fastener carried on the lower face of said hammer head pierces said insulation material and abuts said metal sheet, e. a fastener magazine carried by said carriage, f. feed mechanism carried by said carriage and operable when actuated to deliver a fastener from said magazine and to apply said fastener to the lower face of said hammer head, while said hammer is in its retracted position, with the shank of said fastener directed downwardly, g. manually operable actuating meanS carried by said carriage and operable to actuate said hammer moving means and said feed mechanism, and h. means mounted on said carriage and operable to actuate said hammer whenever it is moved to its advanced position.
 2. The structure as recited in claim 1 wherein said means supporting said carriage above said table includes a fixed horizontal rail disposed above said table and a plurality of rollers mounted rotatably in said carriage and having rolling engagement with said rail, there being at least two of said rollers engaging the upper or lower edge of said rail in spaced apart relation, and at least one of said rollers engaging the other edge of said rail.
 3. The structure as recited in claim 1 wherein said hammer moving means includes means operable to maintain a constant downward pressure on said hammer when said hammer is actuated.
 4. The structure as recited in claim 1 wherein said hammer head constitutes a magnet, said fastener being formed of ferrous material, whereby a fastener applied to said hammer head by said feed mechanism will be magnetically retained thereagainst during the advancement of said hammer.
 5. The structure as recited in claim 4 wherein said feed mechanism includes a feed member carried by said carriage for movement from a retracted position out of the path of said hammer to an advanced position in the path of said hammer when said hammer is retracted, whereby to apply a fastener to said hammer head, the magnetic retention of said fastener on said hammer head permitting said feed member to be retracted before said hammer is advanced.
 6. The structure as recited in claim 5 wherein said manual actuating means is operable to actuate said hammer moving means and said feed mechanism selectively but not concurrently, whereby said hammer and said feed member cannot be advanced simultaneously.
 7. The structure as recited in claim 5 wherein said manual actuating means comprises a lever carried by said carriage for movement in respectively opposite directions from a neutral position, means operable by movement of said lever in one direction to advance said feed member, and to retract said feed member when said lever is returned to neutral, and means operable by movement of said lever in the opposite direction to activate said hammer moving means to advance said hammer, and to actuate said hammer moving means to retract said hammer when said lever is returned to neutral.
 8. The structure as recited in claim 7 wherein said hammer moving means is of a type requiring an appreciable time period after actuation thereof to advance or retract said hammer, and with the addition of interlock means operable responsively to the position of said hammer to lock said lever against movement in said one direction except when said hammer is in its fully retracted position.
 9. An apparatus as recited in claim 8 wherein said interlock means comprises: a. a latch operable when engaged to limit said lever to movement between said neutral position and the position thereof in which it activates said hammer moving means to advance said hammer, b. means connected to and movable with said hammer and operable to disengage said latch whenever said hammer approaches its fully retracted position.
 10. An apparatus as recited in claim 8 wherein said hammer moving means comprises: a. a fluid cylinder mounted in said carriage and having a piston mounted operatively therein, said hammer being connected to and movable by said piston whereby to be advanced and retracted thereby in response to delivery of fluid under pressure to respectively opposite ends of said cylinder, and b. valve means operable to deliver fluid under pressure from a suitable source selectively to either end of said cylinder, said valve normally being operable to deliver fluid to the end of said cylinder to cause retraction of said hammer, said means operable by said lever including means operable by movement of said lever in said opposite direction to operate Said valve to deliver fluid to the end of said cylinder to advance said hammer. 